Conformal mapping modeling of metal plastic deformation and die cavity in special-shaped extrusion

With the help of Complex Function Mapping studied results,the analysis function of Conformal Mapping is set up.Since the complicated three dimension‘s deformation problems are transferred into two dimension problems,both the stream function and strain ratio field are analyzed in the metal plastic deformation.Using the upper-bound principles the theory of metal deformation and die cavity optimized modeling is established for random special-shaped product extrusion.As a result,this enables the realization of intelligent technique arget in the die cavity of CAD/CAM integration.     

Special-shaped tube drawing forming and conformal optimization of die cavity

Aiming at the issues in quick processing and modeling design of drawing special-shaped tube die, by Conformal Mapping Theory and the numerical trigonometry method of interpolation between odd points and even points, the conformal mapping function is obtained. As the result, three-dimension drawing forming were converted into that of two-dimension problems, and the plastic stream function was analyzed, die cavity modeling and its optimized function were set up. Combining with modern processing technology, NC program and CAM of die cavity can be realized. Taking the drawing forming of hexagon tube with arc radii r and ellipse-shaped tube as instances, the drawing die cavity optimization of special-shaped tube was achieved, as well as, the changing principle of wall thickness was analyzed.     

Surface quality of extruding metal special-shape products and frictional behavior in optimized die cavity

With the help of Complex Function Mapping theory, the complicated three-dimensional deformation problems are transferred into two-dimensional problems, and the function of strain ratio field is analyzed in the metal plastic extruding deformation. Taking the strain-hardening effect of metal deformation into account, the relationship between friction behavior and optimized mathematical model is analyzed by the numerical analysis friction energy dissipation function. As a result, the method of lowering the material hardening and decreasing the reduction ratio over multi-procedures can be used to improve the surface quality of metal special-shape extrusion products.     

椭圆异型挤压塑性成形及模腔映射优化

针对非轴对称金属异型挤压塑性流动及模腔研究的理论课题,借助于近代共形映射数学理论研究成果,利用法线收敛法,建立了映射函数解析方法。将三维金属异型材挤压塑性成形问题转化为二维轴对称成形问题,求解椭圆异型挤压金属塑性成形连续流动场和应变速度场的数学解析模型,并应用金属塑性成形理论,建立了精密挤压异型材优化模腔的数学模型,同时为精密快速地实现挤压模腔的CAD／CAM一体化目标提供了技术支持。     

精密挤压(拔制)圆角方型材等相似成形模具映射建模优化

本文针对亟待实现的挤压 (拔制 )异型材模具精密快速加工设计理论课题 ,借助于近代共形映射理论研究成果 ,求解了异型材挤压 (拔制 )模具相似成形塑性流动的数学模型 ,建立了圆角方型材精密挤压 (拔制 )模具模腔数学模型及其优化函数方程 ,建立了为实现模腔精密快速的CAD/CAM一体化的理论模型     

精密挤压金属方型材相似成形与模具映射优化研究

针对圆角方型材精密挤压金属塑性流动描述及相似模具几何参数优化的焦点问题 ,借助于复变共形映射理论 ,建立了表达塑性流动的数学模型及其模具参数 ,塑性体的能量方程 ,实现了模具参数优化及几何解析函数的建立     

精密金属挤压椭圆型材偏心率参数与模腔优化分析

针对非轴对称异型材挤压塑性流动及模腔研究的理论课题 ,借助于近代共形映射数学理论研究成果和塑性成形理论 ,建立椭圆型材精密挤压模腔和金属塑性流动的三维数学模型 ,由椭圆型材截面的偏心率参数变化 ,通过能量极值原理 ,进行挤压载荷比和优化模腔参数规律性分析 ,同时为精密快速实现椭圆型材挤压模腔CAD/CAM一体化的目标提供技术支持     

深孔变壁厚锥形件冷挤压工艺与模具设计

深孔变壁厚锥形件需要3次挤压成形,给出了该零件冷挤压工艺和实用的模具结构,论述了反挤压工序件与成品正挤压模腔的关系,以及凸模和凹模设计。该模具采用伸缩式双级卸料装置,实现较大行程的卸料。     

Hole flanging with cold extrusion on sheet metals by FE simulation

Flange height and lip thickness are generally restricted by the formability of sheet metals in the conventional hole flanging operation. In the current work, cold extrusion was applied and a special forming die set was designed with a stripper subjected to counter-pressure with an aim to obtain a more substantial flange. FEM software DEFORM was utilized to simulate this flange extrusion process with two forming conditions: forming with a fixed die cavity and forming with the stripper subjected to counter-pressure. The results showed the cup preform tended to buckle on its bottom with insufficient counter-pressure. The cup preform would start extruding a flange when critical counter-pressure was reached. The magnitude of the critical counter-pressure increased in flange extrusion of smaller inner diameters. The corresponding overall forming load was greatly reduced as compared to flange extrusion with a fixed die cavity.     

汽车异形齿类零件复合挤压成形技术的优化

分析了汽车零件中1种异形齿形类零件,即离合器轮毂类零件的结构特点及其复合冷挤压成形加工工艺的技术难点,详细阐述了此种类型零件复合冷挤压成形技术的模具设计要点,以及模具的加工、安装和调试。针对现有复合冷挤压成形技术存在的问题,提出了改进优化的方案,设计了改进优化的凹模、凸模以及坯料,通过试验验证了优化的效果。     

An upper bound solution for twist extrusion process

Twist extrusion, a promising severe plastic deformation technique for grain refinement down to ultrafine/nanocrystalline microstructures, was introduced as an attempt to provide large plastic deformation conditions similar to those in high pressure torsion while allowing large workpiece dimensions for industrial applications. As a relatively new severe plastic deformation technique, twist extrusion requires in-depth investigation of its plastic deformation characteristics. In this study, the twist extrusion process with a square shape die cavity has been analyzed using an upper bound solution to estimate the required power, deformation pattern, and optimum process condition. The analysis has been performed based on two kinematically admissible velocity fields while the effects of friction condition, die geometry, and mean equivalent strain have been considered. The results indicate that the die geometry and process parameters can dramatically change the deformation pattern and extrusion power.     

神经网络在模具型腔温升预测中的应用

挤压成形过程中由于坯料和模具之间的滑动接触摩擦和坯料的塑性变形产生热而使模具型腔表面温度升高,加剧模具的磨损。采用热力耦合有限元法计算挤压成形过程中模具型腔表面的温升,将模拟结果与人工神经网络相结合,以有限元模拟结果作为学习样本,训练BP神经网络模型,以此模型预测模具型腔表面的温升。根据预测结果分析了挤压锥角、挤压速度和摩擦系数对型腔温升的影响,为进一步建立挤压成形过程中模具型腔表面的温升模型和磨损预测模型奠定了基础。     

法兰轴温挤压成形工艺分析与挤压凸、凹模参数优化

在分析法兰轴温挤压工艺的基础上,制定了法兰轴的温挤压工艺流程,采用正交试验法对挤压凸、凹模结构参数进行了优化,将优化的凸、凹模结构参数对法兰轴进行温挤压成形试制与验证,得到了合格零件,证明了法兰轴成形工艺方案的正确性。     

三通管挤胀成形过程三维刚塑性有限元模拟中关键问题处理

针对采用三维刚塑性有限元法模拟三通管挤胀成形过程所遇到的一些关键问题, 如有限元计算模型的建立、模具型腔表面的几何描述、动态边界条件处理、空间坐标转换矩阵的推导等,给出了较为通用的处理方法。实际计算过程表明, 所提出的处理方法是有效的、可行的, 有助于提高模拟软件的通用性和自动化程度     

超越离合器壳体的冷挤压成形加工技术

超越离合器壳体是一种具有复杂内孔型腔的盘状类零件,其异型型腔的加工非常困难。通过控制金属流动,采用合适的凸模结构及合理的坯料形状,对离合器壳体内孔型腔进行了冷挤压成形加工。与传统的切削加工工艺相比,采用冷挤压工艺生产的离合器壳体内孔型腔不仅表面光洁度高、尺寸精度高、尺寸一致性好,而且内孔型腔不再后续机械加工就能满足离合器壳体的设计要求;同时还能够节约材料15%～25%、提高生产效率10～15倍。     

Optimum die surface design of general three-dimensional section extrusions by using a surface model with tension parameter

In this paper, an integrated CAD/CAM/CAE method for the optimum die surface design of three-dimensional section extrusions has been proposed. The die surface is represented by a surface model with tension parameter and, therefore, general shapes of products, such as clover, polygonal, T- and L-sections and gear splines which can be designed using only one surface model. Tension parameter is used to obtain the straight line segments when those are required to present the product section. By applying the upper-bound method and the variable metric optimization scheme, the material flow is optimized and a minimum extrusion pressure is obtained. The optimum die surface is subsequently manufactured by using CAD/CAM software and NC machining for making the EDM electrode. Extrusion tests for straight-sided gear splines were performed to obtain the extrusion load and the experimental grid deformation. The theoretical predictions of gear spline extrusion are in close agreement with the experimental results. The numerical results of clover, polygonal, T- and L-shapes are also compared with results available in the literature. The results confirm that better extrusion performance could be obtained with the die surfaces which employed the developed design method. The proposed surface model and the optimum design method can be applied to the die design for general three-dimensional section extrusions.     

A three-dimensional CAD/CAM/CAE integration system of sculpture surface die for hollow cold extrusion

In this paper, a CAD/CAM/CAE integration system for a sculptured surface die for hollow cold extrusion has been developed by using C language for Windows. A sculptured surface model with variable control points is incorporated with a general three-dimensional velocity field to analyze the extrusion process. The profiles of the product and the billet are generated in the CAD module. The fitting points are generated to interpolate the profiles of the product and the billet. The initial guess of control points are created by using the offset of corresponding fitting points in the axial direction. The control points are varied automatically to obtain the optimum die surface by using the upper-bound method and optimization procedure. The CAM module generates the cutter locations by using the optimized die surface model. The gouging areas of the tool path are detected and removed. The calculated cutter locations are verified through the tool path simulation. The NC codes are generated automatically by using the gouging-free cutter locations and then sent directly to a three-axis CNC machine centre to manufacture the EDM electrodes. The extrusion die cavity is made by using an EDM process. Extrusion experiments have verified the proposed CAD/CAM/CAE integration system is successful.     

成形速度对转向节热挤压系统的影响

针对转向节热挤压模具寿命普遍低下的问题,采用有限元数值模拟方法研究了不同成形速度对热挤压系统力、热两方面的影响规律。结果表明:在转向节热挤压过程中,最大挤压力、凹模应力集中区最大主应力、挤压锻件最高温度、模具表层最高温度均随成形速度的增加而增大。这对如何减缓模具失效、提高模具寿命提供了理论参考。     

异型铜材生产工艺优化

针对异型铜材在生产过程中出现的问题进行了研究,通过现场生产试制,对出现问题的原因进行了分析。通过改制生产过程中挤压、拉拔工序的模具、工装及改变挤压、拉拔生产工艺等措施,解决了异型铜材在生产过程中出现的问题。结果表明,改制模具、工装及改变挤压、拉拔生产工艺均可以有效解决异型铜材在生产过程中出现的偏壁、扭拧和力学性能不合等问题。     

塑料异型材挤出模改进

逐步创新、改进设计塑料异型材挤出模,稳定地提高挤出模的设计水平,生产出质量更优越,价格更低廉的产品,更好地推广塑料门窗的使用。